177
additional bit is sent at the end of each frame (known as the frame-
bit or F-bit) so there are 24, 8-bit timeslots, plus 1 bit = 193 bits per
frame.
The synchronization word sent in TS24 is coded as 1 0 1 1 1 Y R 0.
The Y and R are dependent upon the data multiplexer and are for the
manufacturer’s use.
Signalling information is transmitted using ‘stolen’ bits from each
channel, rather than using a separate timeslot as in the European E1
system. Bits are not stolen from timeslots in every frame, because
this would degrade the quality of a voice channel. Instead, the least
significant bit of every sixth frame is used for signalling. Thus the
effective word length of the encoded voice is 7.833 bits, rather than
8 bits of the E1 system.
There are two